1. Field of the Invention
This invention relates to low-profile keyboard switches and, in particular, to a matrix connected keyboard switch with tactile feel for use in small, low cost devices, such as hand-held calculators.
2. Description of the Prior Art
Existing contacting key switches are available in many variations (see Focus on Keyboards Electronic Design, Nov. 7, 1972, pages 54-64). Recent developments include U.S. Pat. No. 3,732,390, entitled Keyswitch by Phillip J. Novak, which includes a key, a base, a sandwiching body of elastic potting material therebetween that resiliently suspends a floating contact, a fixed contact, and leads associated with each contact extending through the base. When pressure is applied to the key, the elastic material is compressed thereby forcing the floating contact into electrical contact with the fixed contact thus completing the external electrical circuit.
A variation of the key switch is U.S. Pat. No. 3,732,387, entitled Key Switch by William A. Berry which includes a convex-conical shaped key supported by a toroidal, helically wound spring. When the key is depressed through an opening in a printed circuit board, the key expands the helically wound spring causing the spring to make contact with the conductors on the printed board.
Thus, existing key switches with tactile feel mechanisms typically have many component parts, difficult assembly techniques and are generally expensive to produce or maintain.